User modes for the major networks

It's been a long time since there was a single type of server used by
all servers. Since then, the various networks have all continued to
develop their own independently of the others. User modes are one of the
things affected by this all but the most standard (i, o and w) have the
same function on all networks. Each network has also added a set of modes
unique to that particular network. This also goes for smaller networks
which usually base their ircds on one of those used by the major networks
but often diverge and add modes of their own or change the behaviour of
existing ones.

These user modes are supported by the server versions current as of the date shown below.
Older versions may be missing one or two modes or have a different
implementation for some. User modes which may be set only by IRC operators
are marked with an asterisk. Others will let themselves be set by
all users but will return very little information for a
non-IRC operator.

The list is based on the following versions which were current as of the date above:
EFnet: 2.8/hybrid-6.2
IRCnet: 2.10.3
DALnet: bahamut 1.4.3
Undernet: u2.10.10